What Causes the Hip Flexor to Lock Up & Give Out? | livestrong

A hip flexor strain, when the muscles are torn or stretched, is an injury that may occur with sudden movements in the hip. This could include jumping, running and changing direction quickly or kicking. … While many conditions that cause the hip flexor to lock up and give out are treatable with rest, ice and over-the-counter medications …

https://www.livestrong.com/article/392261-what-causes-the-hip-flexor-to-lock-up-give-out/